LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

GIFT  OF 

&',M 


Received  cj-  .  ,  1900 

Accession  No. §  /2  0  $  .    Class  No.    - 


•*i 


LABORATORY  MANUAL 


FOR   THE  COURSE   IN 


ELEMENTARY  AND  ECONOMIC 


ENTOMOLOGY 


AT    THE 


UNIVERSITY  OF  CALIFORNIA 


C.  W.  WOODWORTH 


Published  by  the  Author 
BERKELEY,  CAL. 

1893 
Copyrighted. 


T 


FIRST    WEEK.  Vo*, 

NEEDED.*     A  number  of  grasshoppers. 

FIRST  HOUR.  Draw  one  of  the  legs,  naming  the  parts  as  follows: 
Coxa,  trochanter,  femur,  tibia,  tarsus  (three-jointed).  Describe  the 
nature  of  the  union  between  each  of  these  parts.  Compare  each  of 
these  parts  in  the  three  pairs  of  legs,  and  note  particularly:  (a)  Strength- 
ening ridges,  (£)  modifications  of  the  surface  for  the  attachment  of 
muscles,  (c)  guidepieces  at  the  joints,  (d)  position  and  use  of  spines,  (<?) 
pads  on  the  feet—  the  one  at  the  end  is  called  the  pulvillus,  —  (/)  claws 
on  the  feet  —  ungues.  Note  the  number  of  joints  in  the  antenna,  the 
two  basal  ones  (scape  and  pedicel)  somewhat  different  from  the  remain- 
ing part  —  flagellum.  Indicate  the  character  of  the  union  between  these 
parts.  Examine  the  eyes  and  the  simple  eyes  —  ocelli,  describing  their 
shape  and  position. 

SECOND  HOUR.  Remove  the  head  and  pin  it  against  the  cork 
holder.  Observe  the  palpi.  Note  the  number  of  joints  in  each  pair. 
Observe  the  lips  above  or  in  front  —  labrum,  on  the  sides  —  galeae, 
and  below  —  labium.  Draw  the  whole  labium  indicating  the  mentum, 
ligula,  palpi  and  the  lobes  —  lips  proper.  Remove  the  labium, 
exposing  the  maxillae.  Draw  one  of  these,  naming  the  parts  as  fol- 
lows: Cardo,  stipes,  palpifer,  palpus,  galea,  lacinea.  Examine  the 
large  jaws—  mandibles,  beyond  the  maxillae,  and  the  small  basal  piece, 
and  also  the  clypeus  to  which  the  labrum  is  attached. 

THIRD  HOUR.  Insert  a  blunt  pin  into  the  hind  end  of  the  insect, 
pushing  it  forward  until  it  comes  against  the  front  of  the  head,  stretch- 
ing the  neck  well  out.  Observe  now  the  parts  of  which  the  head  is 
composed,  and  indicate  the  relation  of  these  parts  to  the  appendages. 
Attempt  to  trace  by  semi-diagramatic  drawings  the  relation  between 
labium  and  maxillae  and  between  all  the  appendages  of  the  head  and 
legs. 


*The  following  material  is  needed  throughout  the  course: — 

Magnifier.     A  Coddington  or  other  lens  of  about  a  half-inch  focus. 

Cyanide  bottle.  A  small  lump  of  cyanide  of  potash  cemented  to  the  bottom  of  an 
eight  ounce  salt-mouth  bottle  in  plaster  of  Paris. 

Pins.  Klajger  insect  pins  Nos.  1,  3,  and  5  are  recommended,  but  ordinary  pins  do  for 
dissecting. 

Cork  holder.     A  wine  or  other  large  cork  to  pin  the  insect  to  while  studying. 


. 


SECOND    WEEK. 

NKEDED.     A  number  of  grasshoppers. 

FIRST  HOUR.  Examine  the  front  wing,  noticing  the  strong  vein 
extending  to  the  base  (subcostal  vein) ,  and  also  the  other  strong  vein 
(median  vein),  which,  with  the  subcostal  vein,  divides  the  wing  into 
three  more  or  less  equal  parts.  Notice  further  the  costal  vein,  inde- 
pendent vein,  and  submedian  vein  within  these  areas.  Draw  an  out- 
line of  the  wing,  naming  these  parts — costal,  median,  and  internal 
areas,  and  sketch  in  roughly  the  veins  and  their  branches.  Now  on  a 
larger  scale  draw  the  base  of  the  wing,  indicating  accurately  the  num- 
ber and  origin  of  each  vein  in  this  region. 

SECOND  HOUR.  Draw  one  of  the  hind  wings  in  the  same  way  as 
directed  above  for  the  front  wings,  marking  out  very  carefully  the  ho- 
mology  of  the  veins  with  those  of  the  front  wings. 

THIRD  HOUR.  The  three  segments  of  the  thorax  are  called  the 
pro-  meso-  and  metathorax,and  the  same  prefixes  are  used  to  designate 
the  parts  of  each  of  these  segments.  Above  they  are  called  tergum  or 
notum,  the  sides  plurae,  and  beneath  sternum.  The  notum  is  divided 
into  four  tergites  (praescutum,  scutum,  scutellum,  and  postscutellum), 
the  pleurae  into  twopleurites  (episternum  and  epimeron),  and  the  ster- 
num of  each  segment  contains  but  a  single  sternite.  Describe  or  draw 
these  parts  as  they  appear  on  the  grasshopper,  noting  particularly:  (a) 
The  great  size  of  the  pronotum,  (£)  the  absence  of  the  praeepimeron,  (<:) 
the  small  size  of  the  prosternum,  and  (d)  the  dovetailing  between  the 
sternites  of  the  second  and  third  thoracic  and  first  abdominal  segments. 


THIRD  WEEK. 

NEKDED.     A  number  of  grasshoppers,  including  both  sexes. 

FIRST  HOUR.  Study  the  union  of  the  wing  with  the  body.  Make 
a  drawing  both  from  above  and  below.  Examine  the  wing  in  all  posi- 
tions, and  describe  the  action  of  the  hinge  parts. 

SECOND  HOUR.  Draw  the  first  two  abdominal  segments,  making 
out  carefully  the  division  between  the  thorax  and  abdomen.  Draw  on 
a  larger  scale  the  ear.  Notice  the  chitinous  border  of  the  tympanum, 
and  note  the  shape  and  position  of  the  lateral  and  central  processes  of 
the  tympanum.  Notice  the  spiracle  near  the  front  edge  of  the  ear,  and 
note  the  position  of  all  the  spiracles  on  the  insect's  body. 

THIRD  HOUR.  Male.  Draw  carefully  the  end  of  the  abdomen  as 
seen  from  the  side,  numbering  all  the  parts  so  as  to  indicate  the  seg- 
ments to  which  they  appertain.  Now,  grasping  the  abdomen  near  the 
thorax,  slowly  compress  it  until  the  organs  are  widely  spread,  and  draw 
again.  Note  the  cerci,  the  three  anal  flaps  and  the  clasping  organ. 
Female.  Draw  twice  from  the  side,  as  directed  above,  noting  the  cerci, 
the  anal  flaps,  the  four  valves  of  the  ovipositor,  the  egg  guides  and  the 
extensile  glands  between  the  eighth  and  ninth  segments  below.  Try 
to  homologize  the  parts  in  the  two  sexes. 


FOURTH  WEEK. 

NEEDED.  A  sauce  dish.  Some  pasteboard  cut  so  as  to  lay  in  the 
bottom  of  the  dish.  A  sharp-pointed  knife  or  small  sharp-pointed  scis- 
sors. A  number  of  grasshoppers. 

FIRST  HOUR.  With  scissors  or  knife  rip  the  insect  open  along 
the  side  from  end  to  end,  then  putting  a  pin  through  the  head  and  an- 
other through  the  harder  part  of  the  hind  end  of  the  body,  stretch  the 
insect  out  full  length  on  a  piece  of  pasteboard,  putting  in  the  pins  very 
obliquely.  With  other  pins  spread  out  the  body,  exposing  all  the  in- 
ternal structure,  and  place  the  whole  under  water  in  the  sauce  dish. 
Observe  the  digestive  tract,  the  air  sacs,  the  sexual  organs  in  the  abdo- 
men, the  tracheae  in  all  parts  of  the  body,  and,  pulling  the  alimentary 
tract  to  one  side,  notice  the  heart.  Notice  further  the  nervous  system 
along  the  sternum  and  the  muscles  of  the  thorax.  Carefully  dissect 
out  the  digestive  system,  noting  the  pharynx,  with  the  salivary  glands, 
the  aesophagus,  the  crop,  with  the  caeca,  the  stomach,  the  ilium,  with 
the  Malpighian  tubes,  the  colon,  and  the  rectum,  with  the  rectal  glands. 

SECOND  HOUR.  Dissect  out  the  sexual  organs  of  both  sexes,  de- 
scribing their  structure.  Describe  the  size  and  position  of  the  principal 
air  sacs.  Dissect  out  and  describe  the  prominent  parts  of  the  nervous 
system  in  the  body. 

THIRD  HOUR.  Carefully  separate  the  head  from  the  body,  and 
cut  the  wall  of  the  head,  beginning  at  the  mouth  and  running  back  of 
the  eyes,  removing  the  back  part.  Now  pin  the  head  to  pasteboard, 
and,  putting  it  into  water,  make  out  carefully  the  brain,  drawing  and 
describing  it. 


FIFTH    WEEK. 


NEEDED.     A  number  of  rather  large-sized  beetles. 

FIRST  HOUR.  Dissect  out  and  draw  the  mouth  parts  of  at  least 
two  species.  Compare  with  each  other  and  with  those  of  the  grass- 
hopper. Consult  the  introduction  to  LeConte  and  Horn's  Classifica- 
tion of  Coleoptera. 

SECOND  HOUR.  Draw  the  under  side  of  the  thorax  of  at  least 
two  species,  naming  all  the  parts,  and  compare  them  with  the  corres- 
ponding parts  of  the  grasshopper. 

THIRD  HOUR.  Describe  the  beetle  according  to  the  following 
outline: — 


Whole  insect 
Head 

Appendages 
Thorax 

Appendages 
Abdomen 


ACCORDING    TO 


'Size 
Color 

Markings 
Shape 

Sculpture 


SIXTH    WEEK. 

NEEDED.  Dissecting  apparatus  as  for  the  fourth  week.  A  num- 
ber of  butterflies  or  moths  and  caterpillars. 

FIRST  HOUR.  Carefully  study  and  describe  the  mouth  parts. 
Draw  the  venation  of  both  front  and  hind  wings  of  one  or  more  species. 
Indicate  the  homology  between  the  veins  in  the  wings  of  these  insects 
and  those  of  grasshoppers.  For  the  peculiar  terms  used  in  this  order, 
compare  the  introduction  of  Morris'  Synopsis  of  I^epidoptera . 

SECOND  HOUR.  Denude  the  thorax  of  its  scales,  study  and  draw, 
naming  the  parts  exposed.  (The  scales  are  much  more  readily  re- 
moved from  moths  than  from  butterflies.) 

THIRD  HOUR.  Describe  the  peculiarities  of  external  structure  of 
a  caterpillar.  If  the  caterpillar  is  hairy,  remove  the  hairs  with  the 
scissors.  Lay  open  the  body  as  directed  in  the  fourth  week,  and  com- 
pare the  internal  structures  with  those  of  the  grasshopper. 


SEVENTH    WEEK. 

NEEDED.     A  few  slides  and  covers  and  a  number  of  wasps. 

FIRST  HOUR.  Make  careful  dissections  and  drawings  of  the 
mouth  parts,  comparing  them  with  these  already  studied.  For  this 
study,  the  labium  and  maxilla  is  best  seen  mounted  in  water  on  a  slide.  The 
part  should  be  dissected  out  and  placed  upon  a  small  drop  of  water  on 
the  center  of  the  slide,  and  the  cover  glass  laid  on.  Only  enough  water 
to  fill  the  space  between  the  cover  and  the  slide  is  wanted. 

SECOND  HOUR.  Make  careful  drawings  of  the  wings,  making 
out  the  homology  of  those  so  far  studied,  and  also  naming  the  veins 
according  to  the  peculiar  nomenclature  used  in  this  order.  Compare 
the  introduction  to  Cresson's  Synopsis  of  Hymenoptera. 

THIRD  HOUR.     Study  the  thorax  drawing,  and  name  the  parts. 
ELECTIVE  WORK.— Description. 

Weeks  twelve  to  sixteen,  either  wholly  or  in  part,  may  be  devoted 
to  writing  descriptions  of  insects.  One  insect  should  be  described  each 
week.  The  descriptions  should  be  full  and  accurate,  and  consist  of: — 

1 .  Name. 

2.  Short  description  consisting  of:    (a)  Size,  (£)  general  color,   (c) 
striking  peculiarities. 

3.  Full  description,  beginning  at  the  head  and  taking  up  each  part 
in  detail. 

4.  Notes  on  habitat,  etc. 

5.  Number  of  specimens  studied. 

Before  writing  the  description,  carefully  read  at  least  two  recent 
descriptions  of  closely  related  insects,  and  use  the  same  nomenclature. 
It  is  well  to  illustrate  by  figures,  but  the  description  should  be  com- 
plete in  itself,  and  not  depend  upon  the  figures.  The  important  thing 
in  writing  a  description  is  to  distinguish  the  things  which  characterize 
the  insect  as  a  species  from  those,  on  the  one  hand,  which  are  common 
property  of  the  whole  group,  and,  on  the  other,  are  peculiar  to  the 
specimen  or  variety.  This  becomes  much  more  easy  to  do  when  a 
large  number  of  specimens  are  studied,  both  of  the  species  and  of  related 
species.  In  collecting,  therefore,  for  this  purpose  take,  whenever  pos- 
sible, many  of  the  same  kind.  In  writing  a  description  it  often  be- 
comes necessary  to  mutilate  a  specimen.  The  description  should  be 
accompanied,  however,  with  at  least  one  perfect  specimen. 


EIGHTH  WEEK 

In  this  and  the  three  succeeding  weeks  twelve  species  are  to  be  de- 
termined as  nearly  as  may  be  with  the  available  literature.  This 
twelve  must  include  at  least  one  of  each  of  the  following  orders:  Hy- 
menoptera,Lepidoptera,  Diptera,  Coleoptera,  Hemiptera  and  Orthofftera. 
Make  notes  and  drawings  freely  while  making  the  determinations,  and 
note  particularly  the  publications  used  and  the  results  obtained. 

HYMENOPTERA.  Cresson's  Synopsis  is  the  basis  for  determina- 
tions in  this  order.  Consult  also  manuscript  synopses  of  particular 
groups.  For  a  reference  to  the  described  species  compare  Cresson's 
Catalogue  of  the  species  of  Hymenoptera. 

LEPIDOPTERA.  Use  Morris'  Synopsis  of  Lepidoptera  for  the  groups 
represented  therein.  Consult  Smith's  List  of  Lepidoptera  and  also 
manuscript  synopses  and  lists. 

DIPTERA.  Williston's  Synopsis  of  Diptera.  For  the  genera  of 
Orthorapha  not  in  Williston  see  manuscript  synopsis.  For  Cyclorapha 
use  Schiner's  Fauna  Austraica.  For  species  consult  Osten  Sacken's 
Catalogue  of  Diptera  and  manuscript  additions. 

NEUROPTERA.     Use  Hagen's  Synopsis  of  Neuroptera. 

COLEOPTERA.  For  genera  use  LeConte  and  Horn's  Classification 
of  Coleoptera  and  for  species  compare  Henshaw's  Lists  of  Synopses  and 
his  Checklist. 

HEMIPTERA  AND  PHYSOPODA.  Use  synopsis  in  Comstock's  In- 
troduction to  Entomology  and  also  manuscript  synopses  and  lists. 
Compare  Uhler's  Checklist  of  Heteroptera  and  manuscript  list  of  Hom- 
optera. 

ORTHOPTERA.  Use  synopsis  in  Comstock's  Introduction  to  En- 
tomology and  manuscript  synopses  and  lists. 

PSEUDONEUROPTERA.     Use  Hagen's  Synopsis  of  Neuroptera. 

THRYSANURA.  Use  synopsis  in  Comstock's  Introduction  to  En- 
tomology. 

ELECTIVE  WORK.— Determination. 

The  twelfth  to  sixteenth  weeks  may  be  partly  or  wholly  used  for 
further  determinations.  It  is  recommended  that  the  student  devote  him- 
self to  as  small  a  group  as  possible.  Three  species  should  represent 
each  week's  work. 


NINTH    WEEK. 

Three  specimens  of  insects  should  be  determined  this  week.  For 
directions  see  under  eighth  week. 

ELECTIVE    WORK.— Physiology. 

If  this  work  is  elected,  the  whole  of  one  of  the  following  groups 
must  be  done: — 

GROUP  i.  Walking.  Needed:  (a)  For  blueprinting:  solution  of 
citrate  of  iron  and  ammonia,  one  part  to  four  of  water;  solution  of  red 
prussate  of  potash,  one  part  to  six  of  water;  dish  for  sensitizing  bath, 
some  plain  paper  not  too  highly  sized.  (£)  For  tracings:  A  candle, 
some  small  panes  of  glass;  (V)  for  loading:  a  little  wax  or  soft  paraffin, 
some  shot  of  rather  large  size;  \d)  for  experimenting  with,  a  number  of 
insects  of  the  same  species  and  of  rather  large  size. 

TWELFTH  WEEK.  Sensitize  some  paper  by  wetting  one  side  of  it 
with  a  mixture  of  equal  parts  of  the  above  solutions  and  drying.  This 
should  all  be  done  in  the  dark  room.  Blacken  a  sheet  of  glass  by  hold- 
ing it  over  the  burning  candle.  Lay  the  blackened  glass  on  the  table, 
and  cause  an  insect  to  walk  over  it,  and  take  a  blue  print  copy  of  the 
tracing  thus  obtained.  Illustrate  by  diagramatic  sketches  the  method 
of  walking  as  made  out  by  a  study  of  the  tracings.  Fasten  a  blue  print 
of  the  tracing  into  the  book. 

THIRTEENTH  WEEK.  Repeat  the  above,  but  with  mutilated  spec- 
imens, showing  the  method  of  walking  with  five  and  four  legs  instead 
of  the  normal  number. 

FOURTEENTH  WEEK.  Melt  a  little  of  the  wax  or  paraffin  and 
place  a  drop  on  one  end  or  side  of  the  insect  experimented  with,  and 
imbed  in  it  one  or  more  shot  so  as  to  weigh  the  insect  down  on  that 
side  or  end.  Obtain  tracings  as  above  and  compare  the  results  with 
normal  walking.  Repeat  once  or  twice  with  the  load  at  different 
places. 

FIFTEENTH  WEEK.  Obtain  tracings  of  the  same  species  on  in- 
clined surfaces  and  compare  with  the  loaded  and  with  the  normal  walk- 
ing. 

SIXTEENTH  WEEK.  Obtain  tracings  showing  a  change  in  locomo- 
tion due  to  a  sensation,  as  a  touch  or  sound,  and  compare  the  tracings 
before  and  after  the  change  as  well  as  the  transition. 

GROUP  II.  Flight.  Needed:  A  pair  of  small  sharp-pointed 
scissors,  some  wax  or  soft  paraffin,  some  small  shot,  India  ink,  a  small 
camel's  hair  pencil,  a  vial  of  chloroform,  a  number  of  house  flies. 

TWELFTH  WEEK.  Cut  off  an  equal  amount  from  both  wings  of  a 
fly,  and,  allowing  it  to  escape  with  a  normal  fly,  note  the  effect  of 
the  mutilation.  Repeat  two  or  three  times, clipping  off  different  relative 
amounts,  but  always  the  same  on  the  two  sides.  Repeat  two  or  three 
times,  taking  parts  off  from  the  back  edge  only. 

THIRTEENTH  WEEK.  Repeat  the  above  experiments,  mutilating 
only  one  side,  and  note  results. 


TENTH  WEEK. 

Three  species  of  insects  should  be  determined  this  week.  For  di- 
rections see  under  sixth  week. 

ELECTIVE  WORK.— Physiology  (con.) 

FOURTEENTH  WEEK.  Observe  and  note  the  effect  of  loading  the 
body  with  shot  and  the  tip  of  one  and  both  wings  with  wax  or  paraffin. 

FIFTEENTH  WEEK.  Remove  one  and  both  halters  and  note  the 
result.  Darken  the  ocelli  with  India  ink.  and  note  results.  Darken 
also  one  and  both  eyes,  and  both  eyes  and  ocelli.  Note  particularly 
the  significance  of  these  results. 

SIXTEENTH  WEEK.  Slightly  chloroform  a  number  of  flies  and 
compare  their  flight  with  the  normal,  and  also  observe  the  effect  of  plac- 
ing flies  a  short  time  in  a  cyanide  bottle.  Note  particularly  the  signif- 
icance of  these  results  as  compared  with  the  preceding  experiments. 

GROUP  III.  Sensations.  Needed:  Blue  printing  and  tracing 
materials  as  in  group  one,  but  larger-sized  sheets,  at  least  twelve  in- 
ches square.  A  set  of  blocks  Ixlx^  inches  in  size — twelve  white, 
twelve  black,  six  red,  six  blue,  six  yellow  and  six  green.  A  box 
divided  into  six  equal  sections  by  partial  partitions,  with  a  set  of  glass 
covers  for  these  partitions — six  clear,  six  black,  one  red,  one  yellow,  one 
blue  and  one  green.  A  musical  instrument.  A  set  of  vials  containing 
different  odors.  A  quantity  of  insects  of  various  kinds. 

TWELFTH  WEEK.  Blacken  a  sheet  of  glass  and  arrange  the 
black  and  white  blocks  on  it  to  form  a  labyrinth,  so  that  an  insect 
set  in  the  middle  cannot  see  out.  Set  in  w  a  light  where  the 
blocks  will  cast  distinct  shadows  and  liberate  an  insect  in  the  center. 
The  tracing  it  makes  indicates  to  some  extent  its  sight  perception. 
After  the  tracing  is  made  mark  the  outline  of  the  shadows  with  a  pin 
and  also  the  outlines  of  the  blocks,  writing  as  well  the  color  of  each. 
Now  take  a  blue  print  of  the  tracings  and  note  the  significance  of  the 
various  parts. 

THIRTEENTH  WEEK.  Repeat  the  above,  but  with  the  labyrinth 
composed  of  blocks  of  all  colors  to  determine  the  relative  color  percep- 
tion. 

FOURTEENTH  WEEK.  Arrange  the  colored  plates  over  the  sec- 
tions of  the  box  and  liberate  a  number  of  insects,  first  in  one  and  then 
in  another,  and  after  a  short  time  note  in  what  compartments  they  are  to 
be  found,  and  thus  determine  for  each  insect  its  color  preference. 

FIFTEENTH  WEEK.  Place  an  insect  where  it  can  be  carefully 
watched,  and  then  sound  different  tones  on  the  musical  instrument  and 
note  any  evidence  of  sound  perception.  Determine  for  those  evincing 
this  perception  the  pitch  producing  the  most  effect  and  see  if  the  in- 
strument produces  notes  in  either  direction  beyond  their  power  of  per- 
ception. 

SIXTEENTH  WEEK.  Cover  the  sections  of  the  box  with  all  black 
or  all  clear  glass,  according  to  the  nature  of  the  insects  experimented 
with,  and  place  in  each  an  open  vial  containing  an  odor.  Now  by 
liberating  a  number  of  insects,  first  in  one  and  then  in  another,  their 
odor  preference  may  be  determined. 


ELEVENTH  WEEK. 

Three  species  of  insects  should  be  determined  this  week.  For  di- 
rections see  under  eighth  week. 

ELECTIVE  WORK— Physiology  (con.) 

GROUP  IV.  Effect  of  temperature.  Needed:  A  number  of  ther. 
mometers.  A  box  with  glass  cover.  A  watch  or  metronome.  A 
musical  instrument.  A  number  of  small  potted  plants  and  lamp  globes. 
Insects,  some  with  a  visible  heart,  some  with  evident  respiratory 
movements,  some  with  sound  perception,  and  some  plant  lice. 

TWELFTH  WEEK.  Carefully  note  the  temperature  and  count  the 
heart  beat.  Place  the  insect  and  the  thermometer  in  the  box  and  set 
upon  the  stove.  After  raising  the  temperature  about  10  degrees  F.  re- 
move and  wait  till  the  thermometer  begins  to  fall,  and  count  again  the 
heart  beat  Repeat,  raising  the  temperature  about  ten  degrees  at  a  time 
until  it  has  become  uncomfortable  for  the  insect.  If  time  remains,  con- 
tinue the  observations  while  the  box  is  cooling  at  each  temperature  be- 
fore observed. 

THIRTEENTH  WEEK.  Repeat  the  above,  counting  the  respiration 
beats  instead  of  those  of  the  heart. 

FOURTEENTH  WEEK.  Repeat  the  above,  countig  nthe  time  re- 
quired by  a  plant  louse  to  walk  over  a  certain  distance  under  the  differ- 
ent temperatures. 

FIFTEENTH  WEEK.  Try  to  discover  if  there  is  any  difference  due 
to  the  temperature  in  (a)acuteness  of  sound  perception,  (£)pitch  of  best 
perception,  and  (r)range  of  sound  perception. 

SIXTEENTH  WEEK.  The  work  of  this  week  should  be  started  at 
least  six  weeks  before  the  end  of  the  term.  Make  a  number  of  breeding 
cages,  as  directed  under  Life  History  Work,  using,  if  possible  rooted 
plants.  Put  in  each  a  thermometer  and  a  newly  born  plant  louse.  One 
cage  should  be  placed  out-of-doors,  another  in  a  living  room,  and  a 
third,  if  possible,  in  a  still  warmer  place.  It  would  be  well  to  have  two 
in  each  place  to  allow  for  accidents.  The  thermometers  should  be  read 
three  times  a  day  as  regularly  as  possible,  and  the  insects  examined. 
At  the  end  of  six  weeks  the  relative  condition  of  each  cage  should  be 
carefully  noted. 


TWELFTH   WEEK. 

The  work  of  this  and  the  following  weeks  is  to  be  selected  from 
the  work  laid  down  as  elective  work  in  this  manual.  If  work  in  phys- 
iology or  morphology  is  elected  all  five  weeks  must  be  devoted  to  a  sin- 
gle group  in  one  of  these  subjects.  Other  work  may  be  taken  in  any 
combination  of  one-week  units.  The  directions  for  elective  work  will 
be  found  as  follows: — 

Description  under  week  seven; 

Determination  under  week  eight; 

Life  history  under  week  twelve; 

Field  work  under  week  thirteen; 

Physiology  under  weeks  nine  to  eleven; 

Morphology  under  weeks  fourteen  to  sixteen. 

ELECTIVE  WORK.— Life  History. 

The  laboratory  work  of  weeks  twelve  to  sixteen  may  be  repre- 
sented by  investigations  upon  the  life  histories  of  insects.  From  the 
nature  of  this  work  it  cannot  generally  all  be  done  during  these  weeks, 
but  should  be  begun  earlier.  Three  transformations  will  be  considered 
equivalent  to  a  week's  work.  Each  stage  should  be  represented  by  a 
short  descriptive  note  or  sketch  and  by  a  properly  mounted  specimen. 
Thus  four  stages  of  one  insect  would  represent  a  week's  work,  as 
would  two  stages  of  each  of  three  insects.  Parasites  will  be  counted 
as  though  they  were  stages  of  the  insect  studied. 

Eggs  may  be  hatched  by  placing  them  in  a  dry  vial,  stoppered  and 
labeled,  or  they  may  be  at  once  placed  in  breeding  cages,  as  described 
below. 

Larvae  and  nymphs,  if  vegetable  feeders,  may  be  kept  in  a  breeding 
cage  made  as  follows:  A  twig  of  the  food  plant  is  placed  in  a  flowerpot 
filled  with  moist  sand  and  covered  by  a  lantern  or  lamp  globe  which  is 
closed  above  with  a  piece  of  cloth  tied  on.  If  the  larvae  are  young  it 
may  be  necessary  to  renew  the  food  from  time  to  time.  Another 
method  is  to  enclose  the  insect  in  a  cheese-cloth  sleeve  tied  over  the 
twig  upon  which  it  feeds.  A  third  way  is  to  watch  the  insect  as  it  oc- 
curs in  nature,  being  very  careful  that  there  is  no  mistake  in  identity. 
Carnivorous  forms  must  be  supplied  with  their  appropriate  food,  but 
practically  the  same  method  may  be  used. 

Pupae  are  best  kept  in  tight  boxes,  which  should  be  of  a  size  suffi- 
cient to  allow  the  full  expansion  of  the  wings. 

Adults  can  often  be  made  to  lay  their  eggs,  sometimes  by  simply 
confining  the  females  in  a  box;  generally,  however,  it  is  best  to  confine 
her  in  a  breeding  cage  with  the  appropriate  food  for  her  young. 


THIRTEENTH    WEEK. 


The  work  of  this  week  is  elective.  For  directions  see  under 
twelfth  week. 

ELECTIVE    WORK.— Field   Work. 

NEEDED.  Slides,  covers,  glycerine  jelly,  alcohol,  oil  of  cloves, 
and  balsam. 

TWELFTH  WEEK.  In  the  field:  Search  for  a  plant  affected  with 
large  scale  insects.  Note  the  general  appearance  of  the  affected  plant. 
Note  the  abundance  and  distribution  of  the  scale  insects  on  the  plant. 
Look  for  evidences  of  parasitism  and  work  of  predaceous  insects,  collect 
any  specimens  that  may  show  such  work  and  also  twigs  containing 
normal  scales.  In  the  laboratory:  Look  for  eggs  and  young  and  con- 
tinue the  search  for  parasites.  Mount  the  eggs  and  young  if  found,  in 
glycerine  jelly, as  follows:  With  the  point  of  a  penknife  pick  out  a  piece 
of  jelly  about  one  sixteenth  of  an  inch  in  diameter  and  place  on  the  center 
of  a  slide.  Upon  this  place  the  insect  to  be  mounted  and  lay  on  the  cover 
glass  and  gently  heat  until  the  jelly  becomes  fluid.  Examine  under 
the  microscope  and  describe  briefly.  Determine  the  species  by  U.  S. 
Agr.  Report  for  1880. 

THIRTEENTH  WEEK.  In  the  field:  Search  for  a  plant  affected 
with  small  whitish  scales  and  do  as  directed  above  for  the  large  scales. 
In  the  laboratory:  Mount  specimens  of  the  insects  from  beneath  the 
scales  in  glycerine  jelly,  as  directed  above,  and  in  Canada  balsam, as  fol- 
low: Place  the  insects  in  alcohol  five  minutes  and  then  in  oil  of  cloves 
about  the  same  length  of  time.  Now  put  a  small  drop  of  balsam  on 
the  center  of  the  slide  and  the  insect  upon  it,  and  cover.  Warm  gently 
as  before.  Determine  the  species  by  U.  S.  Agr.  Report  for  1880  and 
Cornell  University  Report  for  1882. 

FOURTEENTH  WEEK.  In  the  field:  Turn  over  a  piece  of  sod 
with  a  spade  and  carefully  pick  the  earth  to  pieces  searching  for  root- 
feeding  larvae.  Look  for  and  note  any  evidences  of  injury,  and  collect 
specimens.  In  the  laboratory:  Determine,  as  nearly  as  possible  from 
books  and  the  collection,  the  grcup  of  the  insects  found  and  make  a 
brief  descriptive  note  of  each.  Properly  mount  and  label  each  specimen. 

FIFTEENTH  WEEK.  In  the  field:  Look  for  a  tree  or  fallen  log 
affected  with  borers;  collect  specimens  of  the  insects  and  of  their 
work.  In  the  laboratory:  Determine,  as  nearly  as  possible,  the  insects 
collected.  Make  a  descriptive  note  of  the  insects  and  sketches  showing 
their  work.  Properly  mount  and  label  the  material  collected. 

SIXTEENTH  WEEK.  In  the  field:  Look  for  a  leaf-eating  or  fruit- 
eating  insect  and  collect  specimens.  In  the  laboratory:  Determine, 
mount  and  note  as  above. 


FOURTEENTH    WEEK. 

The  work  of  this  week  is  elective.  For  directions  see  under 
twelfth  week. 

ELECTIVE  WORK.— Morphology. 

If  this  subject  is  elected  the  whole  of  one  of  the  following  groups 
must  be  done: — 

GROUP  I.  Venation  of  grasshopper  wings.  Needed:  Slides, 
large  covers,  alcohol,  oil  of  cloves,  Canada  balsam,  a  number  of 
grasshoppers. 

Mount  all  the  wings  of  at  least  twelve  grasshoppers  in  balsam,  as 
directed  under  field  work,  being  very  careful  to  note  on  each  slide  the 
source  of  each  wing,  also  mount  and  label  the  specimens  from  which  the 
wings  were  taken. 

THIRTEENTH  WEEK.  Make  careful  drawings  of  the  front  and 
hind  wings,  showing  the  principal  veins  in  the  two  most  different 
species. 

FOURTEENTH  WEEK.  Compare  the  two  sides  of  each  insect  and 
describe  the  amount  and  nature  of  the  differences. 

FIFTEENTH  WEEK.  Compare  the  wings  of  different  specimens 
of  the  same  species,  describing  the  amount  and  nature  of  the  differences. 
How  do  these  variations  compare  with  those  found  in  the  two  sides  of 
the  same  specimen  ? 

SIXTEENTH  WEKK.  Compare  the  wings  of  different  species, 
describing  the  amount  and  nature  of  the  differences.  How  do  these 
compare  with  those  within  the  species  ? 

GROUP  II.  The  tongue  of  the  house  fly.  Needed:  Test  tube  or 
beaker,  a  number  of  vials,  needles  in  handles,  camel' s-hair  pencil, 
alcohol,  borax  carmine  solution,  acid  alcohol,  oil  of  cloves,  Canada 
balsam,  slides,  covers,  paraffin  bath,  label,  plate  of  glass,  microtome, 
Schallibaum's  fixative,  microscope,  and  a  number  of  house  flies. 

TWELFTH  WEEK.  Heat  water  to  boiling,  and  after  removing 
from  the  fire,  drop  into  it  the  freshly -removed  heads  of  a  number  of  flies. 
After  three  minutes  remove  the  tongues  from  the  head,  leaving  the 
former  a  half  an  hour  in  50%  alcohol.  They  are  then  placed  in  strong 
alcohol  for  one  hour  and  then  left  over  night  in  borax  carmine.  In  the 
morning  they  are  washed  in  acid  alcohol  and  then  placed  in  strong 
alcohol  till  next  week.  Treat  some  others  in  hot  water  and  then  remove 
and  mount  the  tongues  in  balsam,  as  directed  under  field  work. 


FIFTEENTH  WEEK. 

The  work    of  this  week   is   elective.     For   directions   see   under 

twelfth  week. 

ELECTIVE  WORK.— Morphology  (con.) 

THIRTEENTH  WEEK.  The  tongues  stained  last  week  are  removed 
to  fresh  strong  alcohol  a  few  minutes,  then  to  oil  of  cloves  about  two 
minutes,  until  they  have  become  uniformly  somewhat  clear.  They  are 
now  put  into  barely  melted  soft  paraffin  (50°  C.)  for  one-half  hour,  then 
for  one  hour  into  harder  (55°  C.)  Ladle  out  onto  a  wet  cold  plate  of 
glass,  so  as  to  form  thick  drops  with  a  tongue  in  the  middle  of  each. 
After  they  are  thoroughly  cool  trim  into  rectangular  blocks  and  fasten 
one  by  means  of  a  hot  knife  blade  to  the  object  holder  of  the  microtome 
in  such  a  position  as  to  cut  cross  sections.  Cut  as  thin  as  possible,  ad- 
justing the  temperature  of  the  room  to  the  hardness  and  thickness  of  the 
section,  so  that,  while  the  sections  will  not  wrinkle,  they  will  stick  to- 
gether and  form  a  perfect  ribbon.  Keep  the  order  of  every  section 
very  carefully  should  the  ribbon  break.  Mount  as  follows:  Paint  a  thin 
layer  of  Schallibaum's  fixative  on  a  slide.  Arrange  the  sections  in  the 
order  cut,  using  two  slides  if  one  is  not  enough.  Place  in  the  oven  of 
the  bath  at  55°  C.  five  minutes.  Wash  while  hot  with  turpentine  and 
apply  the  balsam  and  cover  at  once. 

FOURTEENTH  WEEK.  Cut  and  mount  two  more  sets  of  section 
longitudinally  and  at  right  angles  to  each  other. 

FIFTEENTH  WEEK.  Draw  carefully  the  whole  tongue  from  two 
directions. 

SIXTEENTH  WEEK.  Draw  the  two  most  comprehensive  longi- 
tudinal sections  and  a  number  of  cross  sections  and  indicate  on  the 
other  drawings  the  approximate  place  of  these. 

GROUP  III  Developmentoftheplantlou.se.  Needed:  Salt  so- 
lution, alcohol,  oil  of  cloves,  balsam,  glycerine  jelly,  a  watch  glass, 
needles  in  handles,  slides,  covers,  microscope,  a  number  of  plant  lice. 

TWELFTH  WEEK.  Dissect  in  salt  solution  a  full-grown  plant  louse, 
isolating  the  ovaries.  Mount  in  glycerine  jelly  as  directed  under  field 
work  and  examine  under  the  microscope  to  see  if  the  embryos  are  whole 
and  sufficiently  separated  from  each  other  and  from  the  other  tissue. 
Mount  a  good  number  of  slides. 

THIRTEENTH  WEEK.  Dissect  as  above  and  mount  in  balsam  a 
number  of  slides. 

FOURTEENTH  WEEK.  Study  the  slides  and  pick  out  a  series  of 
about  six  stages  in  jelly  and  in  balsam,  showing  the  development  of 
the  young  louse.  Compare  Mark.  Die  Pflanzenlause. 

FIFTEENTH  WEEK.  Draw  the  three  smaller  stages,  naming  all 
the  parts  which  can  be  recognized. 

SIXTEENTH  WEEK.     Draw  the  older  stages  as  above. 


SIXTEENTH  WEEK. 

The  work  of  this  week  is  elective.  For  directions  see  under 
twelfth  week. 

ELECTIVE  WORK.— Morphology  (con.) 

GROUP  IV.  The  cranium  of  the  wasp.  Needed:  A  small  beaker. 
A  wash  bottle.  A  pair  of  small  sharp-pointed  scissors  or  sharp-pointed 
knife.  A  number  of  wasps. 

TWELFTH  WEEK.  Put  about  a  dozen  heads  to  soak  in  the  beaker, 
and  let  them  macerate  for  two  weeks.  Take  other  specimens  and  care- 
fully study  the  external  structure,  drawing  from  above  and  from  before, 
paying  particular  attention  to  traces  of  nearly  obliterated  sutures. 

THIRTEENTH  WEEK.  Draw  and  study  the  head  very  carefully 
from  the  side  and  from  behind. 

FOURTEENTH  WEEK.  Take  the  material  that  has  been  soaking, 
and  with  the  wash  bottle  clean  out  the  inside.  Remove  carefully  the 
mouth  parts  and  antennae.  Put  the  specimens  all  to  soak  again,  taking 
them  out  only  as  needed.  Take  a  specimen,  and  from  the  neck  open- 
ing cut  through  the  head  below  the  eyes  and  antennae.  Dry  and  study 
the  internal  configuration  of  the  crown,  comparing  it  with  the  outside. 
Study  several  specimens. 

FIFTEENTH  WEEK.  Cut  up  the  side  of  the  head  from  the  mouth 
opening  through  the  eyes,  and  study  carefully  the  internal  configura- 
tion of  the  face. 

SIXTEENTH  WEEK.  Cut  in  the  median  line  through  the  neck 
and  mouth  openings  and  study  the  side  of  the  head. 

GROUP  V.  Development  of  the  honeybee.  Needed:  Two  dozen 
three-dram  vials.  Two  watch  glasses.  Two  large  cover  glasses.  A 
comb  of  brood  in  all  stages. 

TWELFTH  WEEK.  Examine  carefully  the  heads  and  determine 
by  their  size  the  number  of  stages  represented.  Take  a  number  of 
each,  including  the  eggs  and  full-grown  bees,  and  place  each  stage  by 
itself  in  vials  of  50  %  alcohol,  and  after  two  hours  change  to  strong  alco- 
hol. Fix  another  set  by  first  treating  in  hot  water,  as  directed  under 
the  second  group,  and  puncturing  in  several  places  before  putting  into 
alcohol. 

THIRTEENTH  WEEK.  Study  the  three  youngest  stages  of  both 
sets,  studying  them  in  alcohol  in  the  watch  glasses.  Be  careful  that 
the  upper  side  of  the  cover  glass  remains  dry.  Describe  the  stages 
and  the  changes  undergone. 

FOURTEENTH  WEEK.  Study  the  remaining  stages  to  where  the 
wing  cases  appear. 

FIFTEENTH  WEEK.     Study  the  stages  bearing  wing  cases. 

SIXTEENTH  WEEK.     Study  the  change  to  the  adult  condition. 


vTBRAtf 
or  THK     ' 

tTNIVERsi 


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